1. Field of the Invention
This invention relates in general to certain new and useful improvements in wheelchairs, and more particularly, to improved wheelchairs which can be constructed in a variety of sizes from standard size components and which also have front and back wheels adjustably mounted thereon.
2. Brief Description of the Prior Art
Wheelchair constructions have remained unchanged, except for relatively minor features, for a substantial period of time. While wheelchairs have existed for many years, they generally were constructed of a main frame, front and rear wheels, side rails or so-called "arm rests" and foot support members. However, there was no means for creating or manufacturing a wheelchair of different sizes, at a relatively low cost, from standard sized components, in order to accommodate different size users.
Prior art wheelchair manufacturers constructed several different sized wheelchairs and used different sized components for each of the differently sized wheelchairs. In the case of a tall individual, the main frame had to be larger, the seat located in a different position, and a foot support member extended further from the seat, than in the case of a wheelchair for a smaller individual. In addition, for the larger sized wheelchair, the seat may have to have been located at a higher elevation in order to permit the user to engage rims on the wheels for propelling the wheelchair in an easy and convenient manner.
Notwithstanding, heretofore there has not been any wheelchair which is designed for anything except normal transport. In other words, wheelchairs heretofore constructed were not designed to permit any form of athletic activity, and particularly, for fast-moving sports activities. This was primarily due to the fact that the prior art wheelchairs were all of a box-like construction with the seat, and hence, the center of gravity, located at a fixed and at a substantial distance above the ground. Consequently, the prior art wheelchairs were not designed for any fast movement, and if one attempted to propel any of the prior art wheelchairs at any significant speed, or attempted to turn a corner quickly, the wheelchair might well tip over creating injury to the user.
In recent years, it has been found to be highly beneficial for paraplegics and others required to use wheelchairs on a relatively permanent basis to engage in various forms of athletic activities, including wheelchair racing, tennis, and the like. However, the wheelchair constructions heretofore did not lend themselves to such form of activities.
For the more seriously handicapped people, particularly with high level back injuries which limited the mobility of these handicapped persons' arms, the conventional wheelchairs are difficult to use. This is due to the heavy construction and weight of the conventional wheelchairs which make it more difficult for the injured party to push and to manuever. As a result, people with such injuries had to resort to the use of motor powered wheelchairs, as for example, electric motor powered wheelchairs which use a battery source of power. These motor powered wheelchairs are quite expensive and require periodic maintenance which thereby militates against widespread use. Further, these wheelchairs require frequent recharging when battery powered.
U.S. Pat. No. 3,937,490 to Nasr discloses a wheelchair having some degree of adjustability to suit several body sizes and deformities. Particularly, the width of the seat and back rest panels may be adjusted, and the length of the seat may be adjusted. However, this patent does not disclose a wheelchair which can be made from a common main frame and in a variety of commonly sized components which are capable of being mounted in a desired location in the same manner as taught and claimed in the instant application. U.S. Pat. No. 4,046,374 to Breyley discloses a walking aid which includes caster wheels. In addition, the walking aid is provided with telescopically located adjustable members.